Chemical Analysis Flashcards
which cations do you test for using the flame method?
Li+, Na+, K+, Ca2+, Cu2+
what cations do you test for using NaOH solution?
NH4+, Cu+, Fe2+, Fe3+, Al3+, Ca2+
Li+ flame colour?
(crimson) red
Na+ flame colour?
orange
K+ flame colour?
lilac
Ca2+ flame colour?
brick red
Cu2+ flame colour?
green
ammonia test?
mix NaOH, heat it up over bunsen burner, and red litmus paper turns blue if positive
Cu2+ and NaOH
creates a blue ppt = Cu(OH)2
Fe2+ and NaOH
creates a green ppt = Fe(OH)2
Fe3+ and NaOH
creates a brown ppt = Fe(OH)3
Al3+ and NaOH
creates a white ppt, but does dissolve excess - so becomes colourless again
Ca2+ and NaOH
creates a white ppt, but doesn’t dissolve excess - stays white
how do you test for sulphates?
adding barium chloride and HCl
why is an acid added for a sulphate test?
gets rid of any unwanted carbonate ions
what happens if it is positive for sulphate?
white ppt
how do you test for halides?
add silver nitrate and nitric acid
what colour ppt is made when positive for Cl-
white ppt
what colour ppt is made when positive for Br-
cream ppt
what colour ppt is made when positive for I
yellow ppt
how to test for carbonates?
add limewater Ca (OH)2 and HCL
what happens when the test is positive for carbonates?
milky/cloudy white & effervescence
test for hydrogen
squeaky pop test
test for oxygen
lit splint test
test for carbon dioxide
limewater
test for water
1) copper sulphate
2) cobalt chloride paper blue to pink
test for chlorine
damp blue litmus paper turns red then white (bleaches)
